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                            <div style="color:gray; word-break: break-all; font-size:12px;">原英文版地址: <a href="https://www.elastic.co/guide/en/elasticsearch/reference/7.7/start-transform.html" rel="nofollow" target="_blank">https://www.elastic.co/guide/en/elasticsearch/reference/7.7/start-transform.html</a>, 原文档版权归 www.elastic.co 所有<br/>本地英文版地址: <a href="../en/start-transform.html" rel="nofollow" target="_blank">../en/start-transform.html</a></div>
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<strong>重要</strong>: 此版本不会发布额外的bug修复或文档更新。最新信息请参考 <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/index.html" rel="nofollow">当前版本文档</a>。
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<h2 class="title">
<a id="start-transform"></a>Start transform API<a class="edit_me edit_me_private" rel="nofollow" title="Editing on GitHub is available to Elastic" href="https://github.com/elastic/elasticsearch/edit/7.7/docs/reference/transform/apis/start-transform.asciidoc">edit</a><a class="xpack_tag" href="https://www.elastic.co/subscriptions"></a>
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<p>Starts one or more transforms.</p>
<div class="section">
<div class="titlepage"><div><div>
<h3 class="title">
<a id="start-transform-request"></a>Request<a class="edit_me edit_me_private" rel="nofollow" title="Editing on GitHub is available to Elastic" href="https://github.com/elastic/elasticsearch/edit/7.7/docs/reference/transform/apis/start-transform.asciidoc">edit</a>
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<p><code class="literal">POST _transform/&lt;transform_id&gt;/_start</code></p>
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<h3 class="title">
<a id="start-transform-prereqs"></a>Prerequisites<a class="edit_me edit_me_private" rel="nofollow" title="Editing on GitHub is available to Elastic" href="https://github.com/elastic/elasticsearch/edit/7.7/docs/reference/transform/apis/start-transform.asciidoc">edit</a>
</h3>
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<p>If the Elasticsearch security features are enabled, you must have the following
built-in roles and privileges:</p>
<div class="ulist itemizedlist">
<ul class="itemizedlist">
<li class="listitem">
<code class="literal">manage_transform</code>
</li>
<li class="listitem">
source index: <code class="literal">view_index_metadata</code>
</li>
</ul>
</div>
<p>For more information, see <a class="xref" href="security-privileges.html" title="Security privileges">Security privileges</a> and <a class="xref" href="built-in-roles.html" title="Built-in roles">Built-in roles</a>.</p>
</div>

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<div class="titlepage"><div><div>
<h3 class="title">
<a id="start-transform-desc"></a>Description<a class="edit_me edit_me_private" rel="nofollow" title="Editing on GitHub is available to Elastic" href="https://github.com/elastic/elasticsearch/edit/7.7/docs/reference/transform/apis/start-transform.asciidoc">edit</a>
</h3>
</div></div></div>
<p>When you start a transform, it creates the destination index if it
does not already exist. The <code class="literal">number_of_shards</code> is set to <code class="literal">1</code> and the
<code class="literal">auto_expand_replicas</code> is set to <code class="literal">0-1</code>.</p>
<p>The transform deduces the mapping definitions from the source indices. For
scripted fields, it uses <a class="xref" href="dynamic-mapping.html" title="Dynamic Mapping">dynamic mappings</a>. If a field in the
destination index is created by <code class="literal">scripted_metric</code> or <code class="literal">bucket_script</code>
aggregations, the transform uses dynamic mappings unless a template exists or
the destination index already exists. Mapping definitions in the destination
index take precedence over dynamic mappings and templates.</p>
<p>When the transform starts, a series of validations occur to ensure
its success. If you deferred validation when you created the
transform, they occur when you start the transform—​with the
exception of privilege checks. When Elasticsearch security features are enabled, the
transform remembers which roles the user that created it had at the
time of creation and uses those same roles. If those roles do not have the
required privileges on the source and destination indices, the
transform fails when it attempts unauthorized operations.</p>
</div>

<div class="section">
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<h3 class="title">
<a id="start-transform-path-parms"></a>Path parameters<a class="edit_me edit_me_private" rel="nofollow" title="Editing on GitHub is available to Elastic" href="https://github.com/elastic/elasticsearch/edit/7.7/docs/reference/transform/apis/start-transform.asciidoc">edit</a>
</h3>
</div></div></div>
<div class="variablelist">
<dl class="variablelist">
<dt>
<span class="term">
<code class="literal">&lt;transform_id&gt;</code>
</span>
</dt>
<dd>
(Required, string)
Identifier for the transform. This identifier can contain lowercase
alphanumeric characters (a-z and 0-9), hyphens, and underscores. It must start
and end with alphanumeric characters.
</dd>
</dl>
</div>
</div>

<div class="section">
<div class="titlepage"><div><div>
<h3 class="title">
<a id="start-transform-example"></a>Examples<a class="edit_me edit_me_private" rel="nofollow" title="Editing on GitHub is available to Elastic" href="https://github.com/elastic/elasticsearch/edit/7.7/docs/reference/transform/apis/start-transform.asciidoc">edit</a>
</h3>
</div></div></div>
<div class="pre_wrapper lang-console">
<pre class="programlisting prettyprint lang-console">POST _transform/ecommerce_transform/_start</pre>
</div>
<div class="console_widget" data-snippet="snippets/2159.console"></div>
<p>When the transform starts, you receive the following results:</p>
<div class="pre_wrapper lang-console-result">
<pre class="programlisting prettyprint lang-console-result">{
  "acknowledged" : true
}</pre>
</div>
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